Solenoid with armature



Sept. 7, 1948. J. G. OETZEL 2,448,727

SOLENOID WITH ARMATURE Filed larch 27, 1944 Patented Sept. 7, 1948 244cmSOLENOID wrrn ABMATUBE John George Oetael, Belolt, Wis., sssignor toWarner Electric Brake Manufacturing Company, Beloit, Wls., a corporationof Illinois Application March 21, 1944, Serial No. 528,194

The present invention pertains to solenoids and the general aim of theinvention is to provide a new and improved solenoid which is capable ofexerting an unusually high force in proportion to its size and weight.

Another object is to provide a novel solenoid having an armatureconcentric with the radially facing pole pieces with which it coacts,the arma- 17 Claims. '(Cl. 175-337) ture and pole pieces beingrelatively movable in an axial direction.

A more detailed object is to provide a solenoid which has a passing typearmature and in which the adjacent portions of the armature and polepieces are shaped relative to each other to effect a progressivediminution in reluctance to flow of flux between the pole pieces andthrough the armature as the latter moves under the influence of suchflux.

Another object is to provide a solenoid having a plurality of pairs ofoutwardly facing pole pieces and an armature ring disposed externally ofsaid pieces and presenting opposite each pole face a surface which isinclined relative thereto.

A further object is to provide a novel solenoid of the above characterwhich lends itself to multiplication of active pole faces to any numberdesired.

Another object of this invention is to provide a solenoid incorporatinga sectional winding and pole pieces intermediately disposed between thewinding sections and cooperatively associated with an armature ofvariable section and reluctance normally biased to displacement alongthe pole pieces in such a way that energization of the winding efi'ectsrelative movement between the pole pieces and armature against thenormal biasing force.

Still another object is to provide a solenoid of the general characterindicated embodying a novel arrangement of the parts which facilitatesthe winding of its actuating coil or coils.

The invention also resides in various structural improvements by meansof which over-all strength and rigidity are achieved in a structure ofsmall size and weight.

Further objects and advantages of the invention will become apparent asthe following description proceeds, taken in connection with theaccompanying drawings in which:

Figure 1 is a vertical sectional view of a solenoid embodying apreferred form of the invention.

Fig. 2 is an exploded perspective view of the solenoid of Fi 1.

Fig. 3 is an enlarged fragmentary sectional.

view, corresponding to the lower portion of Fig. 1, and indicating themean path of fiux flow.

Fig. 4 is a fragmentary sectional view of a structure embodying theinvention in a modified form, and indicating the mean path of flux flowtherein.

While the invention is susceptible of various modifications andalternative constructions, I have shown in the drawings and will hereindescribe in detail the preferred embodiment, but it is to be understoodthat I do not thereby intend to limit the invention to the specific formdisclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit and scope of the inventlon'asexpressed in the appended claims.

In the exemplary embodiment of the invention illustrated in Figs. 1, 2,and 3 of the drawings, the solenoid there shown comprises as itsprincipal elements a core Ill made of suitably magnetizable material andan armature I I having portions made of magnetizable material, as willmore fully be described. The core in of this preferred form consists oftwo concentric ring-shaped members I! and I! having flanges Ila and "arespectively at adjacent ends thereof which are bolted together inoverlapping relation so that the members define between them an annularpocket H' in which is received the annular or drum-shaped armature H.

In the operation of the solenoid the core l0 and armature ll moverelative to each other in an axial direction, one being secured to asupport and the other positioned to move some member which is to beactuated. As here illustrated, the core structure I0 is bolted by meansof an internal mounting flange I'Zb on the inner ring 12 to a stationarysupport shown fragmentarily as two annular members l5, l6, whereas thearmature l I is axially movable to displace any suitable driven element(not shown) that a particular use of the solenoid ma require.

To support the armature ll concentrically with the core i0, and formovement axially oi the same, the flanged outer end I la of the armatureis slidably received on a mounting ring I? of channel-shapedcross-section, fixed to the inner core ring l2. This mounting ring I! ismade of suitable non-magnetic material such, for example, as brass, soas to minimize flux leakage through it.

The armature II is yieldably urged inwardly toward the bottom of thepocket I by suitable spring means and when the solenoid is energized thearmature tends to move outwardly against such spring bias, as willhereinafter appear. Such spring means includes, in the present instance,a ring l8 clamped between the inner core ring I! and the supportingmember I 6 and having thereon a plurality of generally radiallyprojecting integral spring fingers l 8a bent to engage the outer end 01'the armature II and thus urge the armature axially and inwardly into thepocket I4. Such inward movement of the armature is limited by means ofpositive mechanical stops, shown as comprising stop pins l9 fixed to thering flange Ma and received within registering sockets l9a 3 in theinner edge of the armature. These stop pins l9, like the guide ring H,are. preferably aua-rar 4 of'the armatureand pole faces are separated bytwo tapering air gaps of reluctances which vary made oi non-magneticmaterial to minimize any leakage of flux through them and are ofsumcient length to space the innerend of the armature from the adjacentportion of the core to minimize fringing or leakage of flux between thearmature and the inner end of the core.

Opposed pole pieces, preferably in a plurality of pairs spacedlongitudinally of the armature I I, are provided on the core structureit. Desirably, these pole pieces are annular external ribs on the innercore ring l2 having peripheral surfaces which face radially outwardlyand register with the opposed internal faces of annular ribs 2| on theouter core ring it. The ribs 20 and 2| may either be integral with therings l2 and I3, respectively, or may be separately made and pressedonto or otherwise secured to the respective rings. In the presentinstance, the ribs 20 are of somewhat greater radial width than theopposed ribs 2| in order to furnish adequate space for energizingwindings 22. The latter are located in the grooves or channels betweenthe ribs 20 and adjacent the end flange |2a on the inner core ring l2.In constructing the solenoid, the windings 22 may be wound in place onthe exterior of the ring l2 prior to bolting the exterior ring I3 to thelatter, or when separately made ribs 20 are used, the windings may beprewound and assembled onto the ring alternately with the ribs, thussimplifying the formation and installation of the windings.

Various mounting arrangements for the terminals of the windings 22 maybe employed. Herein, a strip of insulating material 25 which serves as amounting block for terminals 26, 21 (Fig. 1) is secured to the innercore ring i2. The three windings being connected in parallel, only twoterminals are required for making connections to the windings.

The mean path of flux set up by the windings 22 is indicated by thearrow lines in Fig. 3. Having in mind that Fig. 3 is a sectional view,it will be apparent that the mean paths throughout the solenoid are ofmore or less toroidal shape and embrace the respective windings. Eitherdirect or alternating current may be used for energizing the windings22, the former being preferred for the illustrated device since its corestructure is not laminated. As appears from the flux paths indicated inFig. 3, the flux flows in orbital paths, passing from one pole piece tothe opposed pole piece radially through the armature, such opposed polepieces being of opposite polarity and formed respectively by theprojections 20 and 2| on the inner and outer members l2 and I3. By wayof example, north and south poles-may be induced as indicated by theletters N and "S" in Fig. 3.

The armature and each of the adjacent portions of the core pole piecesare constructed and arranged for coaction to effect a progressivedecrease in reluctance to the flow of flux between the opposed polepieces as the core and armature move axially relative to each other inone direction from the normal position illustrated. For this purpose,integral annular rings 28 of magnetizable material having a tapered orwedge-like section are provided in the armature l|, one for each pair ofpole pieces on the core. In each instance, these rings 28 have abrupt.or substantially radial end faces and angularly disposed or gentlysloped faces 28a disposed opposite thecylindrical faces of the coactingpair of pole pieces 20 and 2 I. In this way, the active portionsprogressively along the armature in an axial direction. The rings 28 aresupported and secured together by a ring-like supporting and spacingmember 20 which is preferably made of nonmagnetic material, such asbrass, and notched as at to receive the rings 2l-and hold them in spacedrelation to minimize flux leakage between the pole pieces through thearmature. The rings 2| are preferably secured in place in the member 29by non-magnetic welding or brazing- 2|. In consequence of the shape ofthe parts described. the reluctance to flow of flux between the opposedpairs of pole pieces is diminished as the armature moves to the right(as viewed in Fig. 3).

By reason of the high reluctance between the opposite ends of thearmature II and the adjacent portions of the core, as well as betweenthe saparated rings 20, substantially all of the flux threading the coreand armature structure is compelled to flow in the paths indicated inFig. 3. In so doing, it passes transversely through the rings ofmagnetizable material in the armature and links the opposed pole pieces.Since the flux follows in the path of least reluctance, it tends to passthrough the rib portions of the armature as indicated, and the fluxlines tend to straighten, producing an endwise force that urges thearmature to the right as viewed in Fig. 3 or, in other words, in adirection to minimize the air gaps and thus the reluctance.

Referring to the modified form of the invention illustrated in Fig. 4,the solenoid comprises a core 40 and an armature 4| which are both madeof a suitable magnetizable material. The

core 40 includes a ring-like base or connecting portion 42 which hasthereon a plurality of pole pieces 43 which preferably project outwardlyfrom the base or connecting portion 42 and may be integral therewith orseparately made and suitably secured in position. The pole pieces 43 areaxially spaced to provide intermediate channels for winding sections 44.The winding sections 44 may be wound in place when the pole pieces areintegral portions of the core, or may be separately prewound andassembled onto the core when separately made pole pieces are utilized.The core 40 is supported by a non-magnetic bracket 45 and is securedthereto by a bolt 46 having a cooperating spacer 41 for positioning thecore with respect to the support.

The armature 4| is also generally circular in shape and is concentricwith respect to the core 40 and the projecting ends of the pole pieces43. This armature has an inner surface adjacent the core 40 which isshaped or notched to provide similar gradually sloped surfaces, such as48, opposed to the end or pole face of each of the pole pieces 43 andconnected by abrupt or radial intervening surfaces. The armature isbiased by means not shown to a position such as that illustrated and inwhich the heavier or thicker portions of the armature are disposed tothe sides of the pole pieces toward which the armature is biased. Theouter surface of the armature 4| is generally cylindrical.

'of non-magnetizable or magnetizable material,

is secured to a support or bracket 45 by means such as a bolt 53. Thearmature ll carries a member 54 which is adapted to be connected to adevice which is to be actuated by the movement of the armature. Lugs,such as ll, on the outer end surface of the armature engage the member54 to insure the movement of the member 54 with the armature duringoperation.

The mean flux paths in this modified form of the invention, are somewhatdifferent from those disclosed in connection with the preferredembodiment shown in Figs. 1, 2, and 3, although the principle ofoperation of the solenoid is similar. The armature in this instanceprovides the return or connecting path between the ends of the polepieces 43. However, since the tapered or sloped portions of the armatureare normally disposed in positions such that the air gaps at the ends ofthe pole pieces are longer than when the armature is moved to the right,as shown in Fig. 4, the tendency of the flux is to urge the armature toa position such that the air gaps and the resulting reluctances of theflux paths are reduced. It is to be noted that the windings are arrangedin such a way that the polarities of the pole pieces alternate. Also, asin the previously described form, the pole pieces and the coactingportions of the armature are constructed and arranged to effect aprogressive decrease in the reluctance to the flow of flux through thearmature between adjacent pole pieces as the core and armature moveaxially relative to each other in one direction.

Even though there is a diminution of the air gaps as the armature moves,the described construction provides a flow of flux that achieves a highdegree of uniformity of force on the armature throughout a reasonablylong range of permitted movement of the armature. Such range is limitedin the advancing direction for the armature (to the right in Figs. 3 and4) by stops or otherwise, so that the armature is never permitted quiteto touch the pole pieces or pass beyond the position of maximum pull dueto inertia. In the retraction of the armature the range is limited bythe stops IS, in Fig. 3, to a point such that even when the armature isfully retracted no substantial amount of flux will leak from its innerend to the adjacent portion In of the core.

When the windings are deenergized the armature is held in its retractedposition by springs not shown in Fig. 4. Upon energization of thewindings 22, the armature is magnetically pulled toward its projectedposition against the bias of the springs. Open-circuiting the windingspermits the springs to restore the armature to its initial or retractedposition.

I claim as my invention:

1. In an electric solenoid, the combination of a pair of concentricgenerally annular magnetizable members magnetically connected at one endand having radially alined pole pieces facing inwardly and outwardly anddefining circular air gaps between their opposed faces, an energizingwinding for inducing magnetic poles of opposite polarity in said opposedpole pieces to cause flux to pass therebetween through said gaps, anannular armature disposed in said gaps and providing a radial path forthe flux threading between said opposed faces, and means supporting saidcore and armature for relative axial movement, the adjacent surfaces ofsaid armature and pole pieces being shaped to effect a progressivechange in the spacing oi the armature from said pole pieces as thearmature and pole pieces move axially relative to each other.

2. In an electric solenoid, the combination of a core presenting a pairof annular radially alined pole pieces of opposite polarity with an airgap between their opposed faces, means including an energizing windingfor causing flux to pass through said gap between said pole pieces, andan annular armature mounted in said air gap for movement relative to thecore in a direction transverse to the path of flux linking said polepieces and having a reluctance which is difierent at successive pointsalong the armature in the direction of its movement, said armatureserving as a radial path for said flux between said pole pieces.

3. In an electric solenoid, the combination of a core presenting a pairof annular radially alined pole pieces of opposite polarity with an airgap between their opposed faces, means including an energizing windingfor causing flux to pass through said gap between said pole pieces, andan annular armature mounted in said air gap for movement relative to thecore in a direction transverse to the path of flux linking said polepieces, the portion of said armature located between said pole piecesbeing tapered in the direction of armature movement, said armatureserving as a radial path for said flux between said radially alined polepieces.

4. In an electric solenoid, the combination of a core having a pluralityof pairs of annular radially projecting pole pieces thereon presentingopposed concentric faces separated by an annular air gap, means forinducing in said pole pieces magnetic poles of opposite polarity tocause flux to thread said gap, an annular armature disposed in the gapsbetween each pair of pole pieces, and means supporting said armature formovement past said pole faces in a direction substantially parallelingthe latter and generally normal to the path of flux linking such polefaces, the portion of said armature between each pair of pole faceshaving a reluctance which is diii'erent at successive points spacedaxially in the direction of its movement.

5. In an electric solenoid, the combination of a core presenting aplurality of axially spaced pairs of pole pieces with the faces of eachpair opposing each other, an armature disposed in the air gaps betweenthe successive pairs of pole pieces, said armature and pole pieces beingshaped relative to each other to gradually diminish the air gaps betweenthe armature and each pair of pole pieces as the armature and core moverelative to each other across said pole faces in one direction, andmeans for inducing magnetic poles of opposite polarity in the polepieces of each pair.

6. A solenoid having, in combination, a magnetizable core comprising aplurality of axially spaced radially disposed rings, an annular magneticmember joining said rings at corresponding peripheral edges, an annularwinding disposed between the adjacent rings and energizable to producemagnetic poles of alternate polarity at the unjoined peripheral edges ofthe rings, an armature concentric with the faces of said poles, saidpole faces and the opposed surface of said armature being separated byan air gap which tapers axially of said rings, and means supporting saidcore and armature for relative axial movement.

'7. In an electric solenoid, the combination of a magnetizable corestructure defining an annular aerate? outwardly rojecting ole piece withits periphery facing outwardly, a tapered armature ring enclosing saidperipheral face, said ring being movable axially and providing apermeable path for the fiux passing through said pole piece whichincreases in radial thickness upon said ring being subjected to axialmovement, a winding for energizing said pole piece, and means providinga return path for the flux threading said pole piece and armature ring.

8. In an electric solenoid, the combination of a magnetizable corestructure comprising c'oncentric inner and outer rings having theiradjacent side walls spaced apart to form an air gap therebetween, meansforming a low reluctance flux path between said rings at only one end ofsaid gap, a generally drum-shaped armature projecting into said air gapfrom the open end thereof, means supporting said core structure and saidarmature for relative axial movement, said inner and outer core ringshaving a plurality of axially spaced ribs projecting radially with thefaces of the ribs on one ring opposed to those on the other ring todefine poles thereon and radially spaced apart to receive said armaturebetween them, and an energizing winding wound about the exterior of saidinner core ring in the space between two of the ribs thereon.

9. In an electric solenoid, the combination of a magnetizable corestructure presenting a pair of concentric generally annular pole piecesdefining a circular air gap between opposed faces thereof, said corestructure including a portion joining said pole pieces remote from saidgap, an energizing winding for inducing magnetic poles of oppositepolarity in said pole pieces to cause fiux to pass therebetween, anannular armature disposed in said gap in the path of flux threadingbetween said pole pieces, and means for supporting said core andarmature for relative axial movement, said armature having an annularrib presenting a side inclined relative to the face of said pole pieces.

10. A solenoid having, in combination, a magnetizable core comprising aplurality of axially spaced radially disposed rings magnetically joinedat one peripheral edge, an annular winding disposed between the adjacentrings and energizable to produce on the other peripheral edges of therings magnetic poles of alternate polarity, an armature concentric withthe faces of said poles, the surfaces of said armature opposite saidpole faces being frusto-conical to define air gaps which taper axiallyof said rings, and means supporting said armature for axial movement.

11. In an electric solenoid, the combination of a magnetizable corestructure comprising concentric inner and outer rings having theiradjacent side faces spaced apart to form an air gap 'therebetween, meansforming a low reluctance flux path between said rings at only one end ofsaid gap, a generally drum-shaped armature projecting into said air gapfrom the open end thereof, means supporting said core structure and saidarmature for relative axial movement, said inner and outer core ringshaving a plurality of annular ribs on their adjacent faces disposed withthose on one ring radially alined with those on the other to define polepieces thereon and radially spaced apart to receive said armaturebetween them, and an energizing winding disposed about the exterlor ofsaid inner core ring in the space between two of the ribs thereon, saidarmature having annular ribs thereon equal in number to the number ofribs on each of said dill Kilt

core rings and displaced axially from the latter, said armature ribsproviding sidefaces disposed opposite the respective pole faces andinclined relative to the latter. I

12. In an electric solenold,,the combination of a magnetizable coreproviding an annular outwardly facing pole, an armature ring encirclingsaid pole and urged axially by flux threading the two, and a nonmagneticring fixed to said core and guiding said armature for axial slidingmovement.

13. In an electric solenoid, the combination of a magnetizable corestructure including a pair of concentric annular pole pieces defining acircular air gap between opposed faces thereof and an interconnectingmagnetic member bridging said pole pieces, an annular armature disposedin said gap between said pole pieces, an energizing winding for inducingmagnetic poles of opposite polarity in said pole pieces to cause flux tolink said pole pieces through said armature, and means including anonmagnetic stop between said armature-and said interconnecting magneticmember for limiting the movement of said armature with respect to saidmagnetic member.

14. In an electric solenoid, the combination comprising an electromagnethaving windings and pole pieces disposed side by side and alternatingwith each other, said pole pieces being joined on one side of saidwindings by magnetizable material and having exposed pole faces on theother side of the winding, and an armature having active faces angularlydisposed with respect to each of the pole faces, said armature beingsupported adjacent the pole faces in a normal position such thatenergization of the electromagnet tends to move the angularly disposedfaces across said pole faces in a direction to reduce the widths of thegaps between the armature and pole faces.

15. In an electric solenoid, the combination comprising an electromagnethaving a channeled core member providing a pair of connected pole piecesand an energizing winding disposed in the channel between said polepieces, and an armature having substantially wedge-shaped sections ofmagnetizable material adjacent the ends of each of the pole pieces andsupported for movement across the ends of the pole pieces, saidwedge-shaped sections being biased to normal positions in which thethinner portions of the wedges are adjacent the pole pieces.

16. In an electric solenoid the combination comprising a plurality ofpairs of oppositely disposed pole pieces having air gaps therebetween,an armature comprising a plurality of magnetizable members each ofwedge-like section and respectively disposed between the pairs of polepieces, said wedge-like sections being wider than the pole pieces andnormally positioned with the thin end of the section between the polepieces, and non-magnetic means supporting and connecting said membersfor movement transverse to the pole pieces.

17. In an electric solenoid, an armature comprising a plurality ofannular magnetizable members of axially tapered section arranged side byside, means including a nonmagnetic support for maintaining said annularmembers in spaced relation and rigidly fastened to one another to form aunitary cylinder, magnetic structure including a plurality of separatelyenergized annular electromagnets arranged side by side and presentingtheir poles to said annular magnetizable members, the cyclical distancemeasured axially between adjacent ones of sad magnetizable members beingthe same as the cyclical distance between corresponding electromagnetsto cause substantially equal translating iorces to be simultaneously andcumulatively exerted by respective ones of said magnetirable members.

JOHN GEORGE OETZEL.

REFERENCES CITED The following references are of record in the file ofthis patent:

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